A system and method for correcting laser frequency response

Abstract

The present application provides a calibration system and method for the frequency response of a laser, which relates to the technical field of lasers. The system includes: a laser light source module, a signal beam splitting module, a long-delay fiber, a signal beam combining module, a detector module, and a signal acquisition and processing module that are connected in sequence. Among them, when modulating the frequency of the laser signal emitted by the laser light source module, the first modulation signal adopted includes a second modulation signal and a DC modulation signal connected in series. The condition satisfied by the length of the long-delay fiber is: T2 < τ = nL / c < T1. Based on the calibration system and method for the frequency response of the laser provided by the present application, the consistency between the actual frequency response signal and the ideal frequency response signal of the laser can be improved.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a system and method for correcting the frequency response of a laser. Background Art

[0002] Frequency-modulated continuous-wave lidar (FMCW) boasts advantages such as a large measurement range, strong anti-interference capabilities, and high resolution, and has been widely used in target detection, autonomous driving, and other fields. For example, in the field of target detection, a typical FMCW lidar system transmits a modulated laser signal to a target and receives an echo signal reflected by the target. The system then calculates the target's distance, speed, and other information based on the difference frequency signal generated by mixing the detection and echo signals.

[0003] The degree of consistency between the laser's actual response signal and the ideal signal significantly impacts the measurement accuracy of FMCW lidar. In practical applications, when the laser is modulated using linear or nonlinear modulation signals, the difference between the actual laser response signal and the ideal signal can be significant, due to the influence of the laser device itself or the device that generates the modulation signal. This can lead to significant errors in the target measurement results of FMCW lidar-based measurement devices or systems. Summary of the Invention

[0004] The embodiments of the present application provide a system and method for correcting the frequency response of a laser, which can improve the consistency between the actual frequency response signal of the laser and the ideal frequency response signal.

[0005] In a first aspect, an embodiment of the present application provides a system for correcting the frequency response of a laser, the system comprising: a laser light source module, a signal beam splitting module, a long-delay fiber, a signal beam combining module, a detector module, and a signal acquisition and processing module connected in sequence; the laser light source module is used to emit a laser signal and modulate the frequency of the laser signal according to a first modulation signal, the first modulation signal comprising a second modulation signal and a DC modulation signal connected in series; the signal beam splitting module is used to split the laser signal into local oscillator light and test light, the test light is delayed by the long-delay fiber to output a delayed light signal, the signal beam combining module is used to combine the local oscillator light and the delayed light signal into a mixed light signal, the detector module is used to convert the mixed light signal into an electrical signal, the signal acquisition and processing module is used to adjust the second modulation signal according to the electrical signal to obtain a target modulation signal, and the target modulation signal is used to trigger the frequency response of the laser;

[0006] The conditions that the long delay fiber length meets are: Wherein, T2 is the period of the second modulation signal, T1 is the period of the DC modulation signal, τ is the delay time of the test light, L is the length of the long delay fiber, n is the refractive index of the long delay fiber, and c is the speed of light.

[0007] The laser frequency response correction system provided by the present application connects the traditional second modulation signal (i.e., nonlinear modulation signal or nonlinear modulation signal) in series with the DC modulation signal as the first modulation signal to modulate the frequency of the laser signal emitted by the laser. The test light obtained after the laser signal is split is delayed by a long delay fiber. When the delay time is greater than the period of the second modulation signal and less than the period of the DC modulation signal, the region where the frequency changes in the waveform of the delayed optical signal and the region where the frequency changes in the waveform of the local oscillator light are completely non-overlapping, thereby avoiding the delay of the optical signal and the local oscillator light in the beam combining process. The amplitude of the overlapping region changes due to interference, and thus the waveform of the actual response of the laser cannot be obtained. The waveform of the mixed optical signal obtained by the difference frequency of the delayed optical signal and the local oscillator light is closer to the waveform of the actual response of the laser, and the actual response waveform of the laser can be accurately measured by the mixed optical signal. After the mixed optical signal is converted into an electrical signal, the second modulation signal can be adjusted according to the electrical signal to obtain an ideal target modulation signal, so that the actual response waveform of the laser is closer to the ideal response waveform, and the consistency of the actual response signal and the ideal signal is improved.

[0008] Optionally, the laser light source module includes a driving unit, a modulation unit and a laser; the driving unit is connected to the signal acquisition and processing module and the laser respectively, the driving unit is used to drive the laser to emit a laser signal, the modulation unit is used to generate a first modulation signal to modulate the frequency of the laser signal, the signal acquisition and processing module is used to control the driving unit to adjust the second modulation signal according to the electrical signal, and the modulation unit is used to modulate the frequency of the laser signal.

[0009] Optionally, the signal acquisition and processing module includes a signal acquisition unit and a signal processing unit, and the detector module is connected to the signal processing unit through the signal acquisition unit; the signal acquisition unit includes an acquisition card, and the detector module includes a photodetector; the acquisition card is used to intercept the electrical signal according to the period of the second modulation signal to obtain a valid electrical signal; the signal processing unit is used to perform time-frequency conversion processing on the valid electrical signal to obtain a time-frequency response signal, and adjust the second modulation signal according to the relative error between the time-frequency response signal and a preset target time-frequency response signal to obtain a target modulation signal.

[0010] Optionally, the sampling frequency of the acquisition card is greater than twice the frequency modulation bandwidth of the laser, and the bandwidth of the acquisition card and the bandwidth of the photodetector are both greater than the frequency modulation bandwidth of the laser.

[0011] Based on the above optional approach, if the acquisition card's sampling frequency is greater than twice the laser's frequency modulation bandwidth, and the acquisition card's bandwidth is greater than the laser's frequency modulation bandwidth, the acquisition card can fully capture the valid signal within a cycle. Only when the photodetector's bandwidth is greater than the laser's frequency modulation bandwidth can it convert mixed optical signals within a certain frequency range into electrical signals.

[0012] In a second aspect, an embodiment of the present application provides a method for correcting the frequency response of a laser, which is applied to the laser frequency response correction system described in any one of the first aspects. The correction method includes: using a first modulation signal to modulate the frequency of a laser signal emitted by a laser, the first modulation signal including a second modulation signal and a DC modulation signal connected in series; separating the laser signal into local oscillator light and test light, delaying the test light through a long-delay fiber to obtain a corresponding delayed optical signal, combining the local oscillator light and the delayed optical signal into a mixed optical signal, and converting the mixed optical signal into an electrical signal; adjusting the second modulation signal according to the electrical signal to obtain a target modulation signal, the target modulation signal is used to trigger the frequency response of the laser; the condition that the length of the long-delay fiber satisfies is:

[0013] Wherein, T2 is the period of the second modulation signal, T1 is the period of the DC modulation signal, τ is the delay time of the test light, L is the length of the long delay fiber, n is the refractive index of the long delay fiber, and c is the speed of light.

[0014] Optionally, adjusting the second modulation signal according to the electrical signal to obtain a target modulation signal includes: performing time-frequency conversion processing on the electrical signal to obtain a time-frequency response signal; determining a relative error between the time-frequency response signal and a preset target time-frequency response signal; and adjusting the second modulation signal according to the relative error to obtain the target modulation signal.

[0015] Optionally, the second modulation signal is adjusted according to the relative error to obtain a target modulation signal, including: when the relative error does not meet the preset condition, adjusting the second modulation signal according to the relative error, updating the first modulation signal based on the adjusted second modulation signal, and returning to execute the step of modulating the frequency of the laser signal emitted by the laser using the first modulation signal until the relative error meets the preset condition; when the relative error meets the preset condition, determining that the adjusted second modulation signal is the target modulation signal.

[0016] Optionally, determining the relative error between the time-frequency response signal and a preset target time-frequency response signal includes: according to formula E r =(S i -S t ) / S t Determine the relative error between the time-frequency response signal and the preset target time-frequency response signal, where E r is the relative error, S i is the time-frequency response signal, S t is the preset target time-frequency response signal.

[0017] Optionally, adjusting the second modulated signal according to the relative error includes: adjusting the second modulated signal according to the formula U t+1=(1+E r *α)*U t The second modulation signal is adjusted, wherein U t is the second modulation signal, U t+1 is the adjusted second modulation signal, E r is the relative error, and α is a parameter.

[0018] Based on the above optional method, since the difference between the actual time-frequency response signal of the laser and the ideal time-frequency response signal at each moment is different, it is necessary to calculate the relative error between the time-frequency response signal at each moment and the preset target time-frequency response signal, and adjust the second modulation signal at each moment based on the relative error.

[0019] Optionally, performing time-frequency conversion on the electrical signal to obtain a time-frequency response signal includes: intercepting the electrical signal according to the period of the second modulation signal to obtain a valid electrical signal; and performing time-frequency conversion on the valid electrical signal to obtain a time-frequency response signal.

[0020] Based on the above optional method, the period of the time-frequency response signal is the same as the period of the second modulation signal, and within each period, the waveform of the actual time-frequency response signal of the laser is also the same. Therefore, it is only necessary to intercept the effective electrical signal within any period, perform time-frequency conversion on the effective electrical signal, and then adaptively adjust the waveform within any period of the second modulation signal based on the relative error between the time-frequency response signal waveform and the preset time-frequency response signal waveform. This eliminates the need to compare the entire time-frequency response signal with the preset time-frequency response signal, thereby improving computational efficiency and achieving rapid correction of the laser frequency response error.

[0021] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the method described in any two items of the first aspect above.

[0022] In a fourth aspect, an embodiment of the present application provides a computer program product, which, when executed on a terminal device, enables the terminal device to execute any of the methods described in the second aspect above.

[0023] It can be understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions of the beneficial effects brought about by the first aspect and the various possible implementation methods of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 This is a schematic structural diagram of a laser frequency response correction system provided in one embodiment of the present application;

[0026] Figure 2 This is a flow chart of a method for correcting laser frequency response provided in one embodiment of the present application;

[0027] Figure 3 This is a time-frequency curve diagram of a linear modulation signal provided by an embodiment of the present application;

[0028] Figure 4 This is a time-frequency curve diagram of a nonlinear modulation signal provided by an embodiment of the present application;

[0029] Figure 5 This is a calibration result diagram of a laser frequency response provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0031] An FMCW LiDAR system, comprised of a FMCW LiDAR and lasers, can detect target distance, speed, and other information. The degree of consistency between the laser's actual response signal and the ideal signal significantly impacts the FMCW LiDAR's measurement accuracy. In practical applications, due to the influence of the laser itself or the device that generates the modulation signal, when the laser is modulated using linear or nonlinear modulation signals, the difference between the laser's actual response signal and the ideal signal can be significant. This can lead to significant errors in the target measurement results of FMCW LiDAR-based measurement devices or systems.

[0032] In order to solve the above technical problems, the embodiments of the present application provide a system and method for correcting the frequency response of a laser. The system uses a first modulation signal composed of a second modulation signal and a DC modulation signal to modulate the frequency of a laser signal emitted by a laser. After the laser signal is separated into local oscillator light and test light, a long-delay fiber is used to ensure that the frequency variation region in the waveform of the delayed optical signal and the frequency variation region in the waveform of the local oscillator light do not overlap at all. This can avoid the amplitude change of the overlapping region due to interference between the delayed optical signal and the local oscillator light during the beam combining process, so that the waveform of the mixed optical signal obtained by the difference frequency of the delayed optical signal and the local oscillator light is closer to the actual response waveform of the laser. The second modulation signal is adjusted according to the actual response waveform to obtain an ideal target modulation signal, so that the actual response waveform of the laser is closer to the ideal response waveform, thereby improving the consistency between the actual response signal and the ideal signal.

[0033] The technical solution of the present application is described in detail below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0034] In one possible implementation, Figure 1 As shown, the laser frequency response correction system provided by the present application includes a laser light source module, a signal beam splitting module, a long delay fiber, a signal beam combining module, a detector module and a signal acquisition and processing module connected in sequence.

[0035] The laser light source module is configured to emit a laser signal and modulate the frequency of the laser signal according to a first modulation signal. The first modulation signal includes a second modulation signal and a DC modulation signal connected in series with the second modulation signal. The second modulation signal may be a nonlinear modulation signal or a linear modulation signal.

[0036] In one embodiment, a laser light source module may include a driving unit, a modulation unit, and a laser. The driving unit is connected to the signal acquisition and processing module and the laser, respectively. The driving unit is configured to generate a driving current to drive the laser to emit a laser signal. The modulation unit is connected to the laser and configured to generate a first modulation signal to modulate the frequency of the laser signal emitted by the laser. The signal acquisition and processing module is configured to control the driving unit to adjust the second modulation signal based on the electrical signal.

[0037] The signal splitting module splits the laser signal emitted by the laser light source module into local oscillator (LO) light and test light. The LO light is directly transmitted to the signal combining module. The test light is delayed by a long-delay fiber and then output as a delayed optical signal. The signal combining module combines the LO light and the delayed optical signal output from the long-delay fiber into a mixed optical signal.

[0038] In the embodiment of the present application, the length of the long delay fiber satisfies the following conditions:

[0039]

[0040] In formula (1), T2 is the period of the second modulation signal; T1 is the period of the DC modulation signal; τ is the delay time of the test light passing through the long delay fiber; L is the length of the long delay fiber; n is the refractive index of the long delay fiber; and c is the speed of light.

[0041] That is, when the delay of the test light in the long-delay fiber is longer than the period of the second modulation signal and shorter than the period of the first modulation signal, the frequency variation region in the waveform of the delayed optical signal and the frequency variation region in the waveform of the local oscillator light can be completely non-overlapping, thereby preventing interference between the delayed optical signal and the local oscillator light during the beam combining process, which would cause amplitude variations in the overlapping region and prevent the inaccurate acquisition of the laser's actual response waveform. After processing the local oscillator light and the test light using the long-delay fiber and signal splitting module, the waveform of the mixed optical signal can be made closer to the laser's actual response waveform, accurately acquiring the error between the laser's response signal and the ideal signal, and improving the consistency of the response signal with the ideal signal by adjusting the second modulation signal.

[0042] The detector module is used to convert the mixed optical signal output by the signal combining module into an electrical signal. Exemplarily, the detector module includes a photodetector, which can be a single-channel or multi-channel photodetector, depending on the number of optical signals input to the photodetector. The signal acquisition and processing module can adjust the second modulation signal based on the electrical signal to obtain a target modulation signal, which is used to trigger the frequency response of the laser.

[0043] The signal acquisition and processing module includes a signal acquisition unit and a signal processing unit. The detector module is connected to the signal processing unit via the signal acquisition unit. The signal acquisition unit includes an acquisition card. The acquisition card can intercept the electrical signal based on the period of the second modulation signal to obtain a valid electrical signal. The signal processing unit is configured to perform time-frequency conversion on the valid electrical signal to obtain a time-frequency response signal, and adjust the second modulation signal based on the relative error between the time-frequency response signal and a preset target time-frequency response signal to obtain a target modulation signal.

[0044] Furthermore, if the acquisition card's sampling frequency is greater than twice the laser's frequency modulation bandwidth, and its bandwidth is greater than the laser's frequency modulation bandwidth, the acquisition card can completely capture the valid signal within a cycle and fully preserve the information in the electrical signal. Furthermore, if the photodetector's bandwidth is greater than the laser's frequency modulation bandwidth, it can convert mixed optical signals within a certain frequency range into electrical signals.

[0045] Based on the same inventive concept, the present application also provides a method for correcting the frequency response of a laser, which is applied to the correction system for the frequency response of a laser provided in the above embodiment. Figure 2 The method for correcting the laser frequency response provided in this application includes the following steps:

[0046] S100, modulating the frequency of a laser signal emitted by a laser using a first modulation signal, where the first modulation signal includes a second modulation signal and a DC modulation signal connected in series.

[0047] In one embodiment, the second modulation signal may be a linear modulation signal, such as a sawtooth wave modulation signal, a triangular wave modulation signal, etc. Assuming that the linear modulation signal is a triangular wave modulation signal, the first modulation signal may be obtained by adding a long period of DC modulation signal after each cycle (i.e., the minimum cycle) of the triangular wave modulation signal.

[0048] In another embodiment, the second signal may also be a nonlinear modulation signal, such as a sinusoidal modulation signal, a periodic pulse modulation signal, etc. Assuming that the nonlinear modulation signal is a sinusoidal modulation signal, the first modulation signal may be obtained by adding a long period of DC modulation signal after each cycle (i.e., the minimum cycle) of the sinusoidal modulation signal.

[0049] S200: Split the laser signal into local oscillator light and test light, delay the test light through a long delay fiber to obtain a corresponding delayed optical signal, combine the local oscillator light and the delayed optical signal into a mixed optical signal, and convert the mixed optical signal into an electrical signal.

[0050] In order to avoid interference between the local oscillator light and the delayed light signal when they are combined, which causes the amplitude of the two signals to change after the waveform changes overlap, and the actual response waveform of the laser cannot be accurately obtained, the delay time used when the test light passes through the long delay fiber should be greater than the period of the second modulation signal and less than the period of the DC modulation signal, as shown in the above formula (1).

[0051] Exemplary, reference Figure 3 The time-frequency curve of the linear modulation signal shown in FIG. Wherein, the first modulation signal includes a triangle wave modulation signal and a DC modulation signal, Figure 3 (a) includes the time-frequency curve obtained by time-frequency transformation of the local oscillator optical signal and the time-frequency curve obtained by time-frequency transformation of the delayed optical signal. The reference frequency of the local oscillator optical signal and the delayed optical signal are both 193THz and the bandwidth is 2GHz. The delay time of the delayed optical signal relative to the local oscillator optical signal is τ1. Figure 3 As can be seen from (a) in FIG. 1 , after the long delay fiber in the embodiment of the present application delays the test light, the region where the waveform of the delayed light signal changes can completely avoid the region where the waveform of the local oscillator light signal changes. Figure 3(b) is a time-frequency curve of a mixed optical signal obtained by combining the delayed optical signal and the local oscillator optical signal using a signal combining module. The reference frequency of the mixed optical signal is 0 and the modulation bandwidth is 2 GHz.

[0052] refer to Figure 4 The time-frequency curve of the nonlinear modulation signal shown in FIG. Wherein, the first modulation signal includes a sine wave modulation signal and a DC modulation signal, Figure 4 (a) includes the time-frequency curve obtained by time-frequency transformation of the local oscillator optical signal and the time-frequency curve obtained by time-frequency transformation of the delayed optical signal. The reference frequency of the local oscillator optical signal and the delayed optical signal are both 193THz and the bandwidth is 2GHz. The delay time of the delayed optical signal relative to the local oscillator optical signal is τ2. Figure 4 As can be seen from (a) in FIG. 1 , after the long delay fiber in the embodiment of the present application delays the test light, the region where the waveform of the delayed light signal changes can completely avoid the region where the waveform of the local oscillator light signal changes. Figure 4 Figure (b) shows the time-frequency curve of the mixed optical signal obtained by combining the delayed optical signal and the local oscillator optical signal using the signal combining module. The reference frequency of the mixed optical signal is 0 and the modulation bandwidth is 2 GHz. The waveform of the mixed optical signal is closer to the actual response waveform of the laser.

[0053] S300 , adjusting the second modulation signal according to the electrical signal to obtain a target modulation signal, where the target modulation signal is used to trigger the frequency response of the laser.

[0054] In one embodiment, after converting the mixed optical signal into an electrical signal, the trigger time of the trigger signal and the period of the second modulation signal are obtained to intercept the electrical signal, obtaining a valid electrical signal. This is equivalent to intercepting a valid signal within one period. The intercepted valid signal is then subjected to time-frequency conversion to obtain a time-frequency response signal. The relative error between the time-frequency response signal and a preset target time-frequency response signal is determined. Finally, the second modulation signal is adjusted based on the relative error to obtain the target modulation signal.

[0055] It should be noted that the period of the time-frequency response signal is the same as the period of the second modulation signal, and within each period, the waveform of the laser's actual time-frequency response signal is also the same. Therefore, it is only necessary to intercept the effective electrical signal within any period, perform time-frequency conversion on the effective electrical signal, and then adaptively adjust the waveform within any period of the second modulation signal based on the relative error between the time-frequency response signal waveform and the preset time-frequency response signal waveform. This eliminates the need to compare the entire time-frequency response signal with the preset time-frequency response signal, thereby improving computational efficiency and enabling rapid correction of the laser's frequency response error.

[0056] Exemplarily, a method for determining the relative error between the time-frequency response signal and a preset target time-frequency response signal is:

[0057] E r =(S i -S t ) / S t (2)

[0058] In formula (2), E r Represents relative error; S i represents the time-frequency response signal; S t Represents the preset target time-frequency response signal.

[0059] In the embodiment of the present application, since the difference between the actual time-frequency response signal of the laser and the ideal time-frequency response signal is different at each moment within a cycle, it is necessary to calculate the relative error between the time-frequency response signal at each moment and the preset target time-frequency response signal, and adjust the second modulation signal at each moment based on the relative error. Specifically, the second modulation signal can be adjusted using the relative error according to formula (3):

[0060] U t+1 =(1+E r *α)*U t (3)

[0061] In formula (3), U t Represents the second modulation signal; U t+1 represents the adjusted second modulation signal; E r represents the relative error; α is an adjustment parameter, which can be set to different values ​​to adjust the speed of the second modulation signal. t represents the tth moment in a cycle. After adjusting the frequency value of the second modulation signal corresponding to each moment in a cycle, an adjusted second modulation signal is obtained. The updated first modulation signal includes the adjusted second modulation signal and the DC modulation signal in series.

[0062] In one embodiment, adjusting the second modulation signal based on the relative error to obtain a target modulation signal includes: when the relative error does not meet a preset condition, adjusting the second modulation signal based on the relative error, updating the first modulation signal based on the adjusted second modulation signal, and returning to execute steps S100-S300 until the relative error meets the preset condition. If the relative error meets the preset condition, the adjusted second modulation signal is determined to be the target modulation signal. The target modulation signal can make the actual frequency response signal of the laser approach the ideal frequency response signal. Exemplarily, the preset condition can be that the relative error approaches 0, or that the relative error remains the same value or has a small variation after adjusting the second modulation signal multiple times.

[0063] Figure 5 This is a calibration result diagram of a laser frequency response provided in an embodiment of the present application. Figure 5 As shown, assuming that the period of the second modulation signal is a triangle wave modulation signal with a period of 10us and the length of the long delay fiber is 11km, the second modulation signal is corrected according to the laser frequency response correction system and method provided in this application. The correction result is shown in FIG. Figure 5 As shown, when the second modulation signal is not corrected, the laser frequency response curve is as follows Figure 5 As shown in (a) in the figure, the nonlinear error between the ideal waveform and the actual response waveform is about 20%. Figure 5 As shown in (b), (c) and (d) in Figure 1, the actual response waveform gradually approaches the ideal waveform after each correction. Figure 5 As shown in (d), the nonlinear error between the ideal waveform and the actual response waveform is about 0.5%. The laser frequency response correction system and method provided in this application can improve the consistency between the actual laser frequency response signal and the ideal frequency response signal.

[0064] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method described in the above method embodiment is implemented.

[0065] An embodiment of the present application further provides a computer program product, which, when executed on a terminal device, enables the terminal device to implement the method described in the above method embodiment.

[0066] The present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, it can implement the steps of the above-mentioned various method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may at least include: any entity or device capable of carrying the computer program code to a terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electric carrier signal, a telecommunication signal and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk.

[0067] References to "one embodiment" or "some embodiments" in this application mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0068] In addition, in this application, unless otherwise clearly specified and limited, the terms "connection", "connected", etc. should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection between two elements or the interaction relationship between two elements. Unless otherwise clearly specified, ordinary technicians in this field can understand the specific meanings of the above terms in this application according to specific circumstances.

[0069] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A laser frequency response correction system, characterized in that: The system comprises: a laser light source module, a signal beam splitting module, a long-delay fiber, a signal beam combining module, a detector module and a signal acquisition and processing module connected in sequence; The laser light source module is used to modulate the frequency of the laser signal emitted by the laser according to a first modulation signal, wherein the first modulation signal includes a second modulation signal and a DC modulation signal connected in series; The signal beam splitting module is used to split the laser signal into local oscillator light and test light, the test light is delayed by the long delay fiber to output a delayed optical signal, the signal beam combining module is used to combine the local oscillator light and the delayed optical signal into a mixed optical signal, the detector module is used to convert the mixed optical signal into an electrical signal, the signal acquisition and processing module is used to adjust the second modulation signal according to the electrical signal to obtain a target modulation signal, and the target modulation signal is used to trigger the frequency response of the laser; The length of the long delay fiber satisfies the following conditions: Among them, T2 is the period of the second modulation signal, T1 is the period of the DC modulation signal, τ is the delay time of the test light, L is the length of the long delay fiber, n is the refractive index of the long delay fiber, and c is the speed of light.

2. The system according to claim 1, wherein: The laser light source module includes a driving unit, a modulation unit and the laser; The driving unit is connected to the signal acquisition and processing module and the laser respectively. The driving unit is used to drive the laser to emit a laser signal. The modulation unit is used to generate the first modulation signal to modulate the frequency of the laser signal. The signal acquisition and processing module is used to control the modulation unit to adjust the second modulation signal according to the electrical signal.

3. The system according to claim 1 or 2, characterized in that The signal acquisition and processing module includes a signal acquisition unit and a signal processing unit, and the detector module is connected to the signal processing unit through the signal acquisition unit; The signal acquisition unit includes an acquisition card, and the detector module includes a photodetector. The acquisition card is used to intercept the electrical signal according to the period of the second modulation signal to obtain a valid electrical signal; the signal processing unit is used to perform time-frequency conversion processing on the valid electrical signal to obtain a time-frequency response signal, and adjust the second modulation signal according to the relative error between the time-frequency response signal and a preset target time-frequency response signal to obtain the target modulation signal.

4. The system according to claim 3, characterized in that The sampling frequency of the acquisition card is greater than twice the frequency modulation bandwidth of the laser, and the bandwidth of the acquisition card and the bandwidth of the photoelectric detector are both greater than the frequency modulation bandwidth of the laser.

5. A method for correcting the frequency response of a laser, characterized in that: The method applied to the laser frequency response correction system according to any one of claims 1 to 4 comprises: Modulating the frequency of the laser signal emitted by the laser using a first modulation signal, wherein the first modulation signal includes a second modulation signal and a DC modulation signal connected in series; Splitting the laser signal into local oscillator light and test light, delaying the test light through the long-delay fiber to obtain a corresponding delayed optical signal, combining the local oscillator light and the delayed optical signal into a mixed optical signal, and converting the mixed optical signal into an electrical signal; adjusting the second modulation signal according to the electrical signal to obtain a target modulation signal, wherein the target modulation signal is used to trigger the frequency response of the laser; The length of the long delay fiber satisfies the following conditions: Among them, T2 is the period of the second modulation signal, T1 is the period of the DC modulation signal, τ is the delay time of the test light, L is the length of the long delay fiber, n is the refractive index of the long delay fiber, and c is the speed of light.

6. The method according to claim 5, characterized in that Adjusting the second modulation signal according to the electrical signal to obtain a target modulation signal includes: Performing time-frequency conversion on the electrical signal to obtain a time-frequency response signal; Determining a relative error between the time-frequency response signal and a preset target time-frequency response signal; The second modulation signal is adjusted according to the relative error to obtain a target modulation signal.

7. The method according to claim 6, characterized in that Adjusting the second modulation signal according to the relative error to obtain a target modulation signal includes: When the relative error does not meet the preset condition, adjusting the second modulation signal according to the relative error, updating the first modulation signal based on the adjusted second modulation signal, and returning to the step of modulating the frequency of the laser signal emitted by the laser using the first modulation signal until the relative error meets the preset condition; When the relative error satisfies the preset condition, the adjusted second modulation signal is determined to be the target modulation signal.

8. The method according to claim 6, characterized in that Determining the relative error between the time-frequency response signal and a preset target time-frequency response signal includes: According to formula E r =(S i -S t ) / S t Determine the relative error between the time-frequency response signal and the preset target time-frequency response signal, where E r is the relative error, S i is the time-frequency response signal, S t is the preset target time-frequency response signal.

9. The method according to claim 6, characterized in that The adjusting the second modulated signal according to the relative error includes: According to the formula U t+1 =(1+E r *α)*U t The second modulation signal is adjusted, wherein U t is the second modulation signal, U t+1 is the second modulated signal after adjustment, E r is the relative error, and α is a parameter.

10. The method according to any one of claims 6 to 9, characterized in that The performing time-frequency conversion processing on the electrical signal to obtain a time-frequency response signal includes: intercepting the electrical signal according to the period of the second modulation signal to obtain a valid electrical signal; Performing time-frequency conversion on the effective electrical signal to obtain a time-frequency response signal.

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